As the communications technologies develop rapidly, in order to improve a downlink peak rate, downlink multiple input multiple output (MIMO) is introduced in the version Rel-7 of wideband code division multiple access (WCDMA).
In MIMO technologies, a base station (NodeB) sends data to a terminal (UE) through a high speed downlink shared channel (HS-DSCH) of a physical layer, and meanwhile, sends control signaling related to the HS-DSCH through a high speed physical downlink shared control channel (HS-SCCH). After receiving the HS-SCCH, the UE performs demodulation, decoding and the like on the HS-DSCH by using control information borne on the HS-SCCH. Then, the UE generates ACK/NACK information according to a reception situation of the HS-SCCH and whether the HS-DSCH is decoded correctly. In addition, the UE further measures a downlink channel status, generates channel quality indicator (CQI) information, and selects a precoding matrix, which makes channel capacity be maximum, to generate a precoding control indication (PCI). The UE sends the ACK/NACK information, CQI information and PCI information to the NodeB by using an uplink high-speed dedicated physical control channel (HS-DPCCH) to bear them. The NodeB uses the CQI information fed back by the UE as a basis for service scheduling, and performs data channel precoding according to a reported PCI.
It has been determined that MIMO is extremely sensitive to placement of an antenna, so that if only a position status of the antenna is slightly changed, a throughput or signal to noise ratio fluctuates dramatically, and especially in an MIMO mode, when received power from two antennas is not balanced, a probabilistic negative gain is incurred to single stream in MIMO mode compared with legacy HSDPA with single antenna.